1. Field of the Invention
The invention relates to a cutting machine, more particularly to a cutting machine including a splined shaft rotatable about an axis and movable along the axis for switching to different operations.
2. Description of the Related Art
Referring to FIG. 1, a conventional cutting machine 10 is shown to include a machine body 11, a driving unit 12 mounted on the machine body 11, a first piston unit 13 mounted on the machine body 11 and movable along a first axis defined by the first piston unit 13, and a rotary cutter holder 14 mounted rotatably on an outer side of the machine body 11. The cutting machine 10 further includes a first shaft 111 mounted in the machine body 11. The first shaft 111 has one end provided with a shaft gear 1112 meshing with a driving gear 121 of the driving unit 12 for power transmission, and an opposite end extending into the first piston unit 13 and formed with a male spline gear 1111. The first piston unit 13 includes a piston 131, a tubular sleeve 132 journalled and extending into the piston 131 and formed with a long female spline gear 1321 having a portion engaging the spline gear 1111, and a first transmission gear 133 radiating from an outer end of the tubular sleeve 132. The rotary cutter holder 14 includes a holder housing 140, a second shaft 141 extending into the holder housing 140 and having a driven end extending into the tubular sleeve 32 and provided with a male spline gear 1411 engaging another portion of the female spline gear 1321, and a cutter shaft 142 mounted in the holder housing 1401 and coupled to the second shaft 141 and a cutter 143. In such a manner, the first shaft 111 is operable to drive the second shaft 141 and thereby further drive the cutter shaft 142 for driving rotation of the cutter 143. The cutting machine 10 further includes a third shaft 112 mounted in the machine body 11, a second transmission gear 113 mounted to an end of the third shaft 112, an outer race 114 coupled fixedly to the rotary cutter holder 14 and the third shaft 112, an inner race 115 fitted coaxially into the outer race 114 and fixed to the machine body 11, a meshing piston 116 movable to couple the outer and inner races 114, 115 so as to lock the third shaft 112 against rotation, and a driving shaft 117 for driving movement of the meshing piston 116 to thereby decouple the outer and inner races 114, 115 so as to permit rotation of the third shaft 112. The piston 131 is powered by a hydraulic system (not shown) to move away from the rotary cutter holder 14 so as to disengage the female spline gear 1321 of the tubular sleeve 132 from the male spline gear 1411 of the second shaft 141, and to engage the first transmission gear 133 with the second transmission gear 113 to thereby enable the first shaft 111 to drive the third shaft 112. When the driving shaft 117 drives the meshing piston 116 to decouple the outer and inner races 114, 115, the third shaft 112 is operable to rotate the rotary cutter holder 14. On the other hand, when the driving shaft 117 drives the meshing piston 116 to couple the outer and inner races 114, 115, the rotary cutter holder 14 is locked to the machine body 11 through the inner race 115.
Since the female spline gear 1321 is relatively long so as to be able to engage simultaneously the male spline gear 1111 of the first shaft 111 and the male spline gear 1411 of the second shaft 141, it tends to deform and requires a high mechanical strength to prevent deformation from occurring. As such, manufacturing cost thereof is increased and the cutting precision deteriorates after a period of use.